Imageable Embolic Microsphere Animal Model: An Interview With Robert Abraham, MD, FSIR

Editor's note: View related video.

Robert Abraham, MD, FSIR, is an interventional radiologist with Dalhousie University Department of Diagnostic Imaging in Halifax, Nova Scotia. He and his colleagues undertook a study of imageable embolic microspheres (IEMs) in a swine renal artery embolization model. Dr. Abraham presented 30- and 90-day results from the study at the 2016 Annual Scientific Meeting of the Society of Interventional Radiology (SIR). Interventional Oncology 360 spoke with Dr. Abraham about the study at the SIR meeting.

IO360: Tell us about the design of your study. 

Abraham: As you know, the IEMs we have studied are an investigational product and are not yet marketed anywhere. This study has been conducted according to regulatory investigational requirements and a protocol developed based on a swine renal artery model where we performed bilateral partial renal artery embolization in 10 pigs comparing IEMs to a control which in this study was Embosphere (Merit Medical). We compared these products angiographically for embolization effectiveness and for complications such as nontarget embolization, arterial perforation, and arterial rupture post embolization and again prior to necropsy at 1 month and 3 months. Micro-CT and histopathology were performed to compare mechanism of occlusion, embolization effectiveness, and arterial recanalization, and to assess and compare inflammatory response, vascular injury, and vascular damage.

IO360: What did the study find?

Abraham: We were able to directly visualize the IEMs under fluoroscopy permitting real-time monitoring of bead flow and deposition within target arteries. We demonstrated angiographic embolization effectiveness after implantation with no acute complications of perforation, rupture or nontarget embolization for all embolization procedures. After 1-month and 3-month implantation periods, angiographic embolization effectiveness was observed for both IEMs and for the control. No to slight recanalization was noted for the IEMs compared to moderate to extensive levels for the control. Histopathology confirmed corticomedullary infarction at all embolization target sites and a mechanical mechanism of occlusion. Micro-CT demonstrated spatial distribution of IEMs in target arteries, whereas Embosphere could not be identified on CT as they are not radiopaque. Importantly, no significant differences were noted on histopathology between test and control articles with respect to inflammatory reactions and vascular injury, and no device migration was observed.

IO360: About the technique itself, what have you learned about how it works? Any tips for someone looking to use an imageable bead?

Abraham: I think this technology is going to be quite valuable when performing embolization procedures because we will better understand what we are treating, and it will help us to standardize these procedures. Right now, we’re using a surrogate for embolization, which is mixing contrast media with embolic beads such as Embosphere. That does not need to be part of the scenario when using these radiopaque beads as you can directly visualize a stream of beads going to the target tissue. I think it’s going to be eye opening, just like the first time I used the product in an animal model. It was quite exciting to be able to see the beads themselves, virtually equivalent to contrast media being injected, but unlike contrast media that simply passes through the tissue, the IEMs can be seen depositing at the target sites.

IO360: What are the potential benefits to the clinician and the patient for an imageable bead embolization?

Abraham: We can truly understand where the beads are going in real time and we can understand distribution in the target tissue. Right now with other products that have been in the market for many years, we really don’t know where the beads themselves have deposited. What IEMs allow is for the interventional radiologist to truly understand what has been targeted and it can more definitely define endpoints for the embolization procedure. Use of IEMs can also help to reduce the amount of contrast media used during the procedure since we do not need to mix contrast with these beads. In addition, there’s no need to spend time mixing and trying to create a suspension. You literally take the beads and inject them with saline and watch them go toward the target tissue. 

IO360: What further study will there be of this imageable bead?

Abraham: We are working closely with the regulatory bodies in the United States and Europe to bring this exciting product to market as soon as possible and we expect commercial availability next year. We look forward to studying our device in liver cancer and in hypervascular tumors such as uterine fibroids, through clinical trials that will demonstrate the benefits of this highly differentiated product.

IO360: What is the takeaway message for interventional oncology clinicians about this product?

Abraham: We’ve described the distinct advantage of directly visualizing bead deployment during fluoroscopy to allow us to monitor the bead flow and deposition in real time during embolization procedures. As we work through the process to bring this technology to market, we believe the results will show that IEMs will prove to be a valuable product for interventional radiologists and the patients they treat. 

Editor’s note: Dr. Abraham reports that he is chief medical officer and board director for ABK Biomedical, Inc. He also reports patents and stock ownership with ABK Biomedical, Inc.

Suggested citation: Ford J. Imageable embolic microsphere animal model: an interview with Robert Abraham, MD, FSIR. Intervent Oncol 360. 2016;4(5):E89-E91.